1. Field of the Invention
The present invention relates to a vehicular active sound effect generating apparatus for generating a sound effect such as a pseudo-engine sound of a vehicle or the like.
2. Description of the Related Art
Sound effect generating apparatus also referred to as “ASC apparatus (Active Sound Control apparatus)”) have been known in the art as apparatus for enhancing the acoustic effect in the passenger compartments of vehicles. See, for example, U.S. Patent Application Publication No. 2008/0310642 (hereinafter referred to as “US2008/0310642A1”) and U.S. Patent Application Publication No. 2009/0028353 (hereinafter referred to as “US2009/0028353A1”.
US2008/0310642A1 discloses that a delay Zc2 produced by a rear speaker 22b is made longer than a delay Zc1 produced by a front speaker 22a (FIGS. 5 through 6D, paragraphs [0085] through [0102]). The lengths of the delays Zc1, Zc2 may be of not only fixed values, but may be varied depending on an increase or reduction in an engine rotational frequency change Δaf [Hz/second] or a vehicle speed change [km/hour/second] (paragraphs [0141] through [0144]).
US2009/0028353A1 is aimed at providing an active sound effect generating apparatus which is capable of generating natural sound effects ([0008]). In order to achieve the object, the active sound effect generating apparatus 101 disclosed in US2009/0028353A1 has a control means 201 (fourth acoustic adjustor 54 and fifth acoustic adjustor 55) which adjusts the amplitudes of reference signals Sr1, Sr2, Sr3 (intermediate signals Si4, Si5) depending on an engine rotational frequency change Δaf [Hz/second] calculated by an engine rotational frequency change calculator 68 and an accelerator opening Aor [%] detected by an accelerator opening sensor 60, for thereby determining the amplitude of a control signal Sc (Abstract).